Silencer

ABSTRACT

543,055. Silencing gaseous currents. BLANCHARD, J. G. July 4, 1940, No. 11258. [Class 7 (ii)] A silencer, particularly for the intakes of engines, compressors &amp;c. comprises inlet tubes 2 passing through a casing 1 and connected to a transverse tube 4 which projects through the side of the casing for connection to the engine &amp;c. an intermediate tube 5 being arranged eccentrically within the casing so as to form substantially crescent-shaped chambers 6 and 7, the former of which is open to the inner end of the tube 4, and the latter is connected to the tube 4 by apertures 8. The chambers are dimensioned according to the frequencies of the noises to be silenced, and are evacuated by the suction of the intake gases. The casing may be lined with felt or other sound-absorbent 9, and filters 11, 12 may be provided at the open ends of the tubes 2. The chamber 7 may be divided by partitions 15 fitted with connecting-tubes 16. More than one intermediate tube may be provided to form more than two crescent chambers.

Sept, 29, 1942.

J. G. BLANCHARD SILENCER Filed July 14', 1941 2 Sheets-Sheet l 2 Sheets-Sheet 2 'l I; 'l :l I! H l1 5 Il u n f l I l l I l l l /M/WTOR (5590/2 Q- Zcz/ac/a/O Armen/5V J G BLANCHARD SILENCER Flled July 14, 1941 Sept. 29, 1942.

Patented Sept. 29, 1942 SILENCER Joseph George Blanchard, London, England, as-

signer of one-half to Cecil Gordon Vokes, Putney, London, England Application July 14, 1941, Serial No. 402,399 In Great Britain July 4, 1940 11i Claims.

This invention relates to silencers and especially, though not essentially to intake silencers for internal combustion engines, compressors and similar machines.

For convenience of description, the invention will be described with reference to its application to air-intake silencers though it will be understood that the invention is not limited to this application.

One object of the invention is to provide a silencer comprising a plurality of cylindrical tubes of progressively increasing diameter, surrounding cne another one or more of the tubes being eccentrically disposed in relation to the others and with the chambers so formed communicating with a passage for the air through the silencer, these chambers being otherwise closed.

Spaces formed between two eccentrically arranged curved walls of complete inner and outer tubes form what may be called crescents if the walls are actually tangential or intersect; the shape may be modied by one of the tubes being entirely within the other, or if the walls are not actually arcuate. All these shapes are for convenience hereinafter included in the term substantially crescent-shaped.

Another object is to provide an air intake silencer in which the air passes through a tube which communicates with each of a plurality of otherwise closed chambers, substantially crescent-shaped in cross Section, in such a manner as to create a vacuum in these chambers.

Means may be provided to lter the air passing into the silencer.

At loW speeds of an engine with which an air silencer is used, there may be time for air to get back into a Vacuum chamber and for this reason this chamber may be provided with means to retard the action. For instance the chamber may be divided into two parts by a partition with a connecting pipe or the equivalent therethrough.

One typical form will now be described, from which further objects and advantages should be clear.

This form is illustrated by the accompanying drawings in which:

Fig. l is a longitudinal section, and

Fig. 2 is a section on the line II-II.

As illustrated the silencer comprises an outer f cylindrical tube I into which from each end project inlet tubes 2 coaxial with the outer cylinder I. The ends of the cylinder are closed, except for the open ends of these inlet tubes, by annular end plates 3.

A cylindrical tube 4 projects into the cylinder I from one side thereof and the inlet tubes open into the side wall of this side tube.

The side tube projects outside the outer cylinder to provide an outlet for air which enters the apparatus by the two inlet tubes and thence through the side tube to the outlet.

The side tube also extends beyond the two inlet tubes towards the opposite side of the outer cylinder, but finishes some distance from this side.

A cylinder 5 of diameter less than the outer cylinder but greater than the inlet tubes is arranged eccentrically within the outer cylinder and surrounding the inlet tubes. The axis of this intermediate cylinder is parallel to the axis of the outer cylinder and it is tangential to the outside of the inlet tubes and preferably also to the inside of the outer cylinder.

The intermediate cylinder thus divides the annular space between the outer cylinder and the inlet tubes into two crescent shaped chambers 6 and 'i'. The outer of these chambers, 6, cemmunicates with the side tube through the open end thereof and the inner one 'I communicates with the side tube through apertures or slots 8 in the Wall of this side tube. In this way, when the silencer is connected to the air intake of an internal combustion engine or compressor or like source of suction, a primary sound absorbing chamber is formed connected to the outlet tube 4 by an opening opposite to the source of suction, and one or more secondary sound absorbing chambers connected to the outlet tube by a number of apertures in the sides of the latter.

Such arrangements, apart from the particular structural embodiments, form in themselves important parts of the invention.

It will be seen in the illustrated ferm that as air is drawn through the silencer, it passes through the inlet tubes 2 and the side tube 4 creating a vacuum in each of the crescentshaped chambers E and l. It is also to be noted that the entry into these crescent-shaped spaces is at the widest parts cf the crescents.

To the ends of the outer cylinder may be attached lters I I, I2 through which the air passes before reaching the inlet tubes. These iilters are preferably circular in shape and of substantially the saine diameter as the cuter cylinder. They are xed in position by a central screw I3 threaded into a spider I 4 cr the equivalent iixed to the outer cylinder.

When an air silencer is used with an engine running at a low speed, it may happen that there will b-e suiiicient time between suction strckes for the air to get back into the vacuum chamber. To minimise this effect, means may be provided to retard the action. The inner crescent shaped chamber for intance may be divided by partitions I5 transverse to the axis of the cylinder, a pipe IB or the equivalent being provided in each partition to connect the vacuum chambers en opposite sides thereof.

It will be understood that the volumes of the vacuum chambers in silencers according to the invention are selected in accordance With the frequencies of the noises to be silenced.

It is to be noted that the improved silencers described are made up mainly of cylindrical members which are readily formed so that the silencers are simple and inexpensive to manufacture.

The invention is clearly not restricted to the details of the forms described which may be modified Without departure from the broad ideas underlying them.

I claim:

1. In a silencer for pulsating gases the combination of an inlet tube for passage of the gases, a cylindrical second tube surrounding said inlet tube eccentrically and dening with it a substantially crescent-shaped chamber, a cylindrical third tube surrounding said second tube eccentrically and dening With it a second substantially crescent-shaped chamber, and a suction tube to the other dened tubes and having independent communications with each.

2. In a silencer for pulsating gases the combination of a pair of concentric inlet tubes for passage of the gases, a cylindrical third tube surrounding both said inlet tubes-eccentrically and dening With them a substantially crescentshaped chamber, a cylindrical fourth tube surrounding said third tube eccentrically and defining with it a substantially crescent-shaped chamber, and a suction tube transverse to said inlet, third, and fourth tubes and having independently communications with each of said i;

substantially crescent-shaped chambers and to said inlet tubes.

3. In a silencer for pulsating gases the com-A bination of a tube for passage of the gases, a

cylindrical second tube surrounding said first L tube eccentrically and defining with it a substantially crescent-shaped chamber, a cylindrical third tube surrounding said second tube eccentrically and defining with it a second substantially crescent-shaped chamber, and a tube transverse to said above mentioned tubes and having independent communication With each substantially crescent-shaped chamber and said iirstmentioned tube, and a transverse apertured partition dividing one of said substantially crescentshaped chambers.

4. In a silencer for pulsating gases the combination of a tube for passage of the gases, a cylindrical second tube surrounding said rst tube eccentrically and dening with it a substantially crescent-shaped chamber, a cylindrical third tube surrounding said second tube eccentrically and defining with it a second substantially crescent-shaped chamber, and a tube transverse to said above mentioned tubes and having independent communications with said substantially crescent-shaped chambers and With the iirst-mentioned tube, a transverse partition dividing one of said substantially crescent-shaped chambers, the said partition having an aperture and a tube disposed in the said aperture.

5. In a silencer for pulsating gases the combination of a pair of concentric inner tubes for passage of the gases, a cylindrical third tube surrounding both said inner tubes eccentrically and dening with them a substantially crescentshaped chamber, a cylindrical fourth tube surrounding said third tube eccentrically and defining with it a substantially crescent-shaped chamber, and a tube transverse to said abovementioned tubes and having independent communication with each of said substantially crescent-shaped chambers, and with said inner tubes a pair of transverse partitions dividing one of said substantially crescent-shaped chambers at each side of said transverse tube, the said partitions having apertures.

6. In a silencer for pulsating gases the combination of a pair of concentric inner tubes for passage of the gases, a cylindrical third tube surrounding both said inner tubes eccentrically and defining with them a substantially crescentshaped chamber, a cylindrical fourth tube surrounding said third tube eccentrically and dening with it a substantially crescent-shaped chamber, and a tube transverse to said abovementioned tubes and having independent communication with each of said substantially crescent-shaped chambers, and with said inner tubes a pair of transverse partitions dividing one of said substantially crescent-shaped chambers at each side of said transverse tube, the said partitions having apertures and tubes disposed in the said apertures.

7. A silencer for the air intake of an internal combustion engine or compressor comprising the combination set out in claim 2, together With ltering means mounted at each end of the tube assembly and giving access of filtered air to the said inner tubes.

8. A silencer for the air intake of an internal combustion engine or compressor comprising the combination set out in claim 1, together with sound absorbent material lining the outermost of the said tubes.

9. In a silencer for pulsating gases the combination of a pair of concentric inner tubes for passage of the gases, a cylindrical third tube surrounding both said inner tubes eccentrically and dening With them a substantially crescentshaped chamber, a cylindrical fourth tube surrounding said third tube eccentrically and dening with it a substantially crescent-shaped chamber, and a tube transverse to the abovementioned tubes and having independent communication with both said substantially crescentshaped chambers at their Widest parts and With both said inner tubes.

10. In a silencer for pulsating gases the combination of a pair of concentric inner tubes for passage of the gases, a cylindrical third tube surrounding both said inner tubes eccentrically and dening with them a substantially crescentshaped chamber, a cylindrical fourth tube surrounding said third tube eccentrically and dening with it a substantially crescent-shaped chamber, and a tube transverse to the abovementioned tubes and having independent communication With both said substantially crescentshaped chambers, with both said inner tubes and open to the source of the sound to be silenced, a pair of transverse partitions dividing one of said substantially crescent-shaped chambers at each side of said transverse tube, the said partitions having apertures at the widest parts of the crescents, and tubes disposed in the said apertures.

JOSEPH GEORGE BLANCHARD. 

